I've been adding IP addresses to our site's block list to prevent bots from chewing up our bandwidth (which happened last month, in an incident separate from the december-january IP scare). Most are known Chinese spambot IP ranges, but there's always a chance I'll accidently hit someone who's a legit member.

So if you see a 403 Forbidden page, it is almost definitely because I accidently blocked your IP, and the only way you're ever getting back in is if I'm contacted to unblock the IP, or if your IP changes. (and changing your IP won't be reliable since a lot of what is blocked are entire ranges, not specific IPs).